Such a vane cell machine is, for example, used as amplification pump behind a pressure converter in a circuit of a reverse osmosis system. In a reverse osmosis system water, for example saltwater, is pumped through a membrane, so that purified water is available at its outlet side.
With this application, a certain difficulty lies in the fact that water cannot be used for lubrication of the mutually moving parts to the same extent as other fluids, particularly oil or oil-containing fluids.
It is therefore known in connection with mutually moving surfaces to use a material pair that interacts unfrictionally also or particularly during operation with water as fluid. When using steel as metal for one element of the material pair, the material for the second element can be selected from the group of high-resistant thermo-plastic plastic materials on the basis of polyaryletherketones, in particular polyetheretherketones, polyamides, polyacetals, polyarylethers, polyethyleneterephtalates, polyphenylensulfides, polysulphones, polyethersulphones, polyetherimides, polyamidimides, polyacrylates, phenol-resins, such as novolacquer-resins, and glass, graphite, polytetraflourethylene or carbon, particularly as fibers, can be used as filler. When using such materials, the vane cell machine can also be operated with water.
However, in spite of the use of such material pairs, it has turned out that internal leakages appear which can be blamed on wear.